Sunday, July 8, 2007

How to reduce violence? Get the Lead Out!

Most people, including those who agree there has been too much criminalization of social problems in contemporary America, assume that serious violent crime problems calls for serious criminal justice solutions. The dramatic declines in violent crime during the 1990s have set off a gold rush of efforts to explain what worked, and most of the answers are criminal justice centered, whether incarceration or better police tactics. A minority have suggested non-criminal justice explanations, including better employment prospects in the 1990s and better access to abortions in the 1970s (the famous Freakonomics explanation). Now comes another explanation in that direction that appears to have good econometrics and, importantly, cross national comparative data (I'm only going on the Washington Post account however).

As reported by Shankar Vendantam in today's Washington Post a new study by economist Rick Nevin suggests that reductions in lead exposure starting in the 1980s closely tracks the locations and temporal pattern of crime reductions in the 1990s. Lead has a documented clinical effect on the brain linked to violence and impulse-control problems. Now Nevin shows that in two very different cycles Americans have been exposed to lead, followed by increases in violent crime, and then by violence reductions after the input of lead to the environment is reduced. The first took place in the early years of the 20th century through the introduction of lead in household paint. The second was automobile based in the post-World War II era. The model suggests that young kids exposed to lead produce higher levels of violence when they age into their crime-prone years. Reducing lead leads to reductions 10 or fifteen years later.

Nevin also has a nice explanation for currently spiking homicide rates in some cities (despite the continued absence of lead from gasoline). Most of this crime, he argues, is being produced by aging recidivists who grew up before lead reductions. That means that our current criminal justice policies, especially heavy use of prisons and barriers to re-entry for ex-prisoners, is itself a major sustainer of violence.

If the best way to govern problems like violent crimes actually lie far from criminal justice, in fields like the environment, it is likely to be even more true of problems like drug addiction, homelessness, and indiscipline in schools.